The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Douglas Marthaler - One of the best experts on this subject based on the ideXlab platform.
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serotype and genotype multilocus sequence type of streptococcus suis isolates from the united states serve as predictors of pathotype
Journal of Clinical Microbiology, 2019Co-Authors: April A Estrada, Marcelo Gottschalk, Stephanie Rossow, Aaron Rendahl, Connie J Gebhart, Douglas MarthalerAbstract:ABSTRACT Streptococcus suis is a significant cause of mortality in piglets and growing pigs worldwide. The species contains pathogenic and commensal strains, with pathogenic strains causing meningitis, arthritis, endocarditis, polyserositis, and septicemia. Serotyping and multilocus sequence typing (MLST) are primary methods to differentiate strains, but the information is limited for strains found in the United States. The objective of this study was to characterize the diversity of 208 S. suis isolates collected between 2014 and 2017 across North America (mainly the United States) by Serotyping and MLST and to investigate associations between subtype and pathotype classifications (pathogenic, possibly opportunistic, and commensal), based on clinical information and site of isolation. Twenty serotypes were identified, and the predominant serotypes were 1/2 and 7. Fifty-eight sequence types (STs) were identified, and the predominant ST was ST28. Associations among serotypes, STs, and pathotypes were investigated using odds ratio and clustering analyses. Evaluation of serotype and ST with pathotype identified a majority of isolates of serotypes 1, 1/2, 2, 7, 14, and 23 and ST1, ST13, ST25, ST28, ST29, ST94, ST108, ST117, ST225, ST373, ST961, and ST977 as associated with the pathogenic pathotype. Serotypes 21 and 31, ST750, and ST821 were associated with the commensal pathotype, which is composed of isolates from farms with no known history of S. suis-associated disease. Our study demonstrates the use of Serotyping and MLST to differentiate pathogenic from commensal isolates and establish links between pathotype and subtype, thus increasing the knowledge about S. suis strains circulating in the United States.
Moon H Nahm - One of the best experts on this subject based on the ideXlab platform.
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from quellung to multiplex pcr and back when needed in pneumococcal Serotyping
Journal of Clinical Microbiology, 2012Co-Authors: Lotta Siira, Moon H Nahm, Tarja Kaijalainen, Lotte Lambertsen, Maija Toropainen, Anni VirolainenAbstract:All currently available vaccines against Streptococcus pneumoniae are based on selections of the over 90 different serotypes, which underlines the importance of Serotyping for surveillance and vaccine efficacy monitoring. In this study, we modified and validated a PCR-based scheme for deducing the serotypes of the invasive pneumococci isolated in Finland. For validation, 170 isolates were serotyped using the new protocol with six sequential multiplex PCRs for the deduction of serotypes, supplemented with Quellung testing when needed. The results were compared with those obtained by traditional Serotyping methods. We found that 98.8% (168/170) of the isolates were correctly serotyped by the new protocol. Subsequently, the scheme was taken into regular use for Serotyping the invasive pneumococci isolated in Finland for serotype-specific surveillance purposes and has been applied in the Serotyping of more than 1,500 invasive isolates so far. The sequential multiplex PCRs (mPCRs) have given a result for over 99% of the isolates and allowed us to both handle samples in bulk and noticeably reduce the cost of reagents. While Serotyping primarily by PCR is precise and effective, Quellung testing remains the most reliable way to discover possible discrepancies between the DNA deduced and the phenotypic serotype of an isolate. Since implementing the protocol for regular use, two serotype 19F PCR-positive isolates were found to be serotype 19A by the Quellung reaction. While a rare occurrence, this is an important observation, which prompted a revision of our Serotyping protocol to prevent possible underreporting of serotype 19A, a potential replacement serotype following large-scale vaccination.
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development of an automated and multiplexed Serotyping assay for streptococcus pneumoniae
Clinical and Vaccine Immunology, 2011Co-Authors: Jisheng Lin, William H Benjamin, Kyung Hyo Kim, Moon H NahmAbstract:Streptococcus pneumoniae expresses more than 90 capsule types, and currently available pneumococcal vaccines are designed to provide serotype-specific protection. Consequently, Serotyping of pneumococcal isolates is important for determining the serotypes to be included in pneumococcal vaccines and to monitor their efficacy. Yet Serotyping of pneumococcal isolates has remained a significant technical challenge. By multiplexing many assays, we have now developed a simple yet comprehensive Serotyping assay system that can not only identify all known pneumococcal serotypes but also subdivide nontypeable (NT) isolates into those with or without the conventional capsule locus. We have developed this assay system to require only six key reagents: two are used in one multiplex inhibition-type immunoassay, and four are required in two multiplex PCR-based assays. The assay system is largely automated by a seamless combination of monoclonal antibody-based and PCR-based multiplex assays using the flow cytometric bead array technology from Luminex. The assay system has been validated with a panel of pneumococci expressing all known pneumococcal serotypes and was found to be easily transferable to another laboratory.
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differential effects of pneumococcal vaccines against serotypes 6a and 6c
The Journal of Infectious Diseases, 2008Co-Authors: In Ho Park, Bernard Beall, Matthew R Moore, John J Treanor, Stephen I Pelton, Tamara Pilishvili, Mark Shelly, Barbara E Mahon, Moon H NahmAbstract:Background Because classical pneumococcal Serotyping cannot distinguish between serotypes 6A and 6C, the effects of pneumococcal vaccines against serotype 6C are unknown. Pneumococcal vaccines contain 6B, but do not contain 6A and 6C.
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rapid multiplex assay for Serotyping pneumococci with monoclonal and polyclonal antibodies
Journal of Clinical Microbiology, 2005Co-Authors: Jisheng Lin, William H Benjamin, Ken B Waites, Chehung Lee, Moon H NahmAbstract:We have developed and characterized a rapid semiautomated pneumococcal Serotyping system incorporating a pneumococcal lysate preparation protocol and a multiplex Serotyping assay. The lysate preparation incorporates a bile solubility test to confirm pneumococcal identification that also enhances assay specificity. The multiplex Serotyping assay consists of 24 assays specific for 36 serotypes: serotypes 1, 2, 3, 4, 5, 6A, 6B, 7A/7F, 8, 9L/9N, 9V, 10A/10B/39/(33C), 11A/11D/11F, 12A/12B/12F, 14, 15B/(15C), 17F, 18C, 19A, 19F, 20, 22A/22F, 23F, and 33A/33F. The multiplex assay requires a flow cytometer, two sets of latex particles coated with pneumococcal polysaccharides, and serotype-specific antibodies. Fourteen newly developed monoclonal antibodies specific for common serotypes and a pool of polyclonal rabbit sera for some of the less-common serotypes are used. The two monoclonal antibodies specific for serotypes 18C and 23F recognize serotype-specific epitopes that have not been previously described. These monoclonal antibodies make the identification of the 14 common serotypes invariant. The specificity of the Serotyping assay is fully characterized with pneumococci of all known (i.e., 90) serotypes. The assay is sensitive enough to use bacterial lysates diluted 20 fold. Our Serotyping system can identify not only all the serotypes in pneumococcal vaccines but also most (>90%) of clinical isolates. This system should be very useful in Serotyping clinical isolates for evaluating pneumococcal vaccine efficacy.
Jisheng Lin - One of the best experts on this subject based on the ideXlab platform.
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development of an automated and multiplexed Serotyping assay for streptococcus pneumoniae
Clinical and Vaccine Immunology, 2011Co-Authors: Jisheng Lin, William H Benjamin, Kyung Hyo Kim, Moon H NahmAbstract:Streptococcus pneumoniae expresses more than 90 capsule types, and currently available pneumococcal vaccines are designed to provide serotype-specific protection. Consequently, Serotyping of pneumococcal isolates is important for determining the serotypes to be included in pneumococcal vaccines and to monitor their efficacy. Yet Serotyping of pneumococcal isolates has remained a significant technical challenge. By multiplexing many assays, we have now developed a simple yet comprehensive Serotyping assay system that can not only identify all known pneumococcal serotypes but also subdivide nontypeable (NT) isolates into those with or without the conventional capsule locus. We have developed this assay system to require only six key reagents: two are used in one multiplex inhibition-type immunoassay, and four are required in two multiplex PCR-based assays. The assay system is largely automated by a seamless combination of monoclonal antibody-based and PCR-based multiplex assays using the flow cytometric bead array technology from Luminex. The assay system has been validated with a panel of pneumococci expressing all known pneumococcal serotypes and was found to be easily transferable to another laboratory.
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rapid multiplex assay for Serotyping pneumococci with monoclonal and polyclonal antibodies
Journal of Clinical Microbiology, 2005Co-Authors: Jisheng Lin, William H Benjamin, Ken B Waites, Chehung Lee, Moon H NahmAbstract:We have developed and characterized a rapid semiautomated pneumococcal Serotyping system incorporating a pneumococcal lysate preparation protocol and a multiplex Serotyping assay. The lysate preparation incorporates a bile solubility test to confirm pneumococcal identification that also enhances assay specificity. The multiplex Serotyping assay consists of 24 assays specific for 36 serotypes: serotypes 1, 2, 3, 4, 5, 6A, 6B, 7A/7F, 8, 9L/9N, 9V, 10A/10B/39/(33C), 11A/11D/11F, 12A/12B/12F, 14, 15B/(15C), 17F, 18C, 19A, 19F, 20, 22A/22F, 23F, and 33A/33F. The multiplex assay requires a flow cytometer, two sets of latex particles coated with pneumococcal polysaccharides, and serotype-specific antibodies. Fourteen newly developed monoclonal antibodies specific for common serotypes and a pool of polyclonal rabbit sera for some of the less-common serotypes are used. The two monoclonal antibodies specific for serotypes 18C and 23F recognize serotype-specific epitopes that have not been previously described. These monoclonal antibodies make the identification of the 14 common serotypes invariant. The specificity of the Serotyping assay is fully characterized with pneumococci of all known (i.e., 90) serotypes. The assay is sensitive enough to use bacterial lysates diluted 20 fold. Our Serotyping system can identify not only all the serotypes in pneumococcal vaccines but also most (>90%) of clinical isolates. This system should be very useful in Serotyping clinical isolates for evaluating pneumococcal vaccine efficacy.
Dan Xiong - One of the best experts on this subject based on the ideXlab platform.
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one step pcr detection of salmonella pullorum gallinarum using a novel target the flagellar biosynthesis gene flhb
Frontiers in Microbiology, 2016Co-Authors: Dan Xiong, Li Song, Shizhong Geng, Jing Tao, Zhiming PanAbstract:Salmonella enterica serovar Pullorum/Gallinarum is an important infectious pathogen that has caused widespread problems for chicken industry. Traditional Salmonella Serotyping is an expensive and time-consuming process. In this study, we developed a rapid one-step polymerase chain reaction (PCR) method to identify S. Pullorum/Gallinarum. The PCR-based assay focuses on flhB, which shows a deficient region only in S. Pullorum/Gallinarum, compared with that of other serovars. The specificity and sensitivity of the PCR system were evaluated. The developed PCR method could identify S. Pullorum/Gallinarum from 27 different Salmonella serovars and eight non-Salmonella pathogens. The minimum limit of DNA and the lowest number of cells of S. Pullorum for the PCR detection were no less than 5.85 pg/μL and 10 CFU, respectively. The method was applied to the analysis of Salmonella strains isolated from the chicken farm. The PCR-based testing results of the farm isolates were in concordance with those obtained using traditional Serotyping method. This newly developed PCR-based system could be used to accurately screen for the presence of S. Pullorum/Gallinarum, and support traditional Serotyping methods, especially in high-throughput screening situations.
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one step pcr detection of salmonella pullorum gallinarum using a novel target the flagellar biosynthesis gene flhb
Frontiers in Microbiology, 2016Co-Authors: Dan Xiong, Li Song, Shizhong Geng, Shumin An, Xinan JiaoAbstract:Salmonella enterica serovar Pullorum/Gallinarum is an important infectious pathogen that has caused widespread problems for chicken industry. Traditional Salmonella Serotyping is an expensive and time-consuming process. In this study, we developed a rapid one-step PCR method to identify S. Pullorum/Gallinarum. The PCR-based assay focuses on flhB, which shows a deficient region only in S. Pullorum/Gallinarum, compared with that of other serovars. The specificity and sensitivity of the PCR system were evaluated. The developed PCR method could identify S. Pullorum/Gallinarum from 27 different Salmonella serovars and eight non-Salmonella pathogens. The minimum limit of DNA and the lowest number of cells of S. Pullorum for the PCR detection were no less than 5.85 pg/μL and 10 CFU, respectively. The method was applied to the analysis of Salmonella strains isolated from the chicken farm. The PCR-based testing results of the farm isolates were in concordance with those obtained using traditional Serotyping method. This newly developed PCR-based system could be used to accurately screen for the presence of S. Pullorum/Gallinarum, and support traditional Serotyping methods, especially in high-throughput screening situations.
April A Estrada - One of the best experts on this subject based on the ideXlab platform.
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serotype and genotype multilocus sequence type of streptococcus suis isolates from the united states serve as predictors of pathotype
Journal of Clinical Microbiology, 2019Co-Authors: April A Estrada, Marcelo Gottschalk, Stephanie Rossow, Aaron Rendahl, Connie J Gebhart, Douglas MarthalerAbstract:ABSTRACT Streptococcus suis is a significant cause of mortality in piglets and growing pigs worldwide. The species contains pathogenic and commensal strains, with pathogenic strains causing meningitis, arthritis, endocarditis, polyserositis, and septicemia. Serotyping and multilocus sequence typing (MLST) are primary methods to differentiate strains, but the information is limited for strains found in the United States. The objective of this study was to characterize the diversity of 208 S. suis isolates collected between 2014 and 2017 across North America (mainly the United States) by Serotyping and MLST and to investigate associations between subtype and pathotype classifications (pathogenic, possibly opportunistic, and commensal), based on clinical information and site of isolation. Twenty serotypes were identified, and the predominant serotypes were 1/2 and 7. Fifty-eight sequence types (STs) were identified, and the predominant ST was ST28. Associations among serotypes, STs, and pathotypes were investigated using odds ratio and clustering analyses. Evaluation of serotype and ST with pathotype identified a majority of isolates of serotypes 1, 1/2, 2, 7, 14, and 23 and ST1, ST13, ST25, ST28, ST29, ST94, ST108, ST117, ST225, ST373, ST961, and ST977 as associated with the pathogenic pathotype. Serotypes 21 and 31, ST750, and ST821 were associated with the commensal pathotype, which is composed of isolates from farms with no known history of S. suis-associated disease. Our study demonstrates the use of Serotyping and MLST to differentiate pathogenic from commensal isolates and establish links between pathotype and subtype, thus increasing the knowledge about S. suis strains circulating in the United States.
